Disposable beverage containers are widely used in the fast food industry for serving coffee, soft drinks and the like. It has long been recognized as desirable to provide disposable beverage containers that include a fill line. The fill line provides the consumer with a reference point in order to establish a consistent measure of volume of the beverage purchased. The fill line is also advantageous because it provides those serving the public with a reference point to indicate a full measure of liquid while ensuring adequate space in the top of the container to accommodate a lid without spillage.
Fill lines are particularly desirable in hot beverage containers. It is well known that hot beverage containers are constructed differently than cold beverage containers and they require a different type of lid. Cold beverage containers are coated both inside and outside. The coating, typically a wax or a plastic polymer, enhances the transmission of heat through the container sidewall. This makes the drink feel cold, which is deemed desirable. It also promotes a good seal with the lid, so cold beverage container lids are flat with a depending skirt that locks over the rim of the container to contain the cold liquid. Hot beverage containers are only coated on the inside, however, because an outer coating would make the containers too hot to be handled. Consequently, it is more difficult to achieve a liquid tight seal with a lid. To inhibit leakage, the lid for a hot beverage container is designed to fit within the mouth of the container so that an internal depending skirt of the lid contacts the inner coated sidewall of the container to improve the seal. If the container is overfilled with hot liquid, some liquid is forced over the rim when a lid is applied. This spillage can be misinterpreted by consumers as resulting from a leaky container, and they may request that the container and the liquid be replaced. It is therefore desirable to provide containers, and in particular hot beverage containers, with a fill mark to avoid this problem.
It is known that a bead or fill line in a beverage container such as a paper cup can be formed by utilizing a spinning forming disc, the disc being spun into a position near the top of the sidewall of the paper container thereby creating a bead, groove or fill line in the sidewall of the container. This apparatus requires a cam follower in a machined cam track, and a cam drive shaft in a relatively complicated header assembly as well as an auxiliary loader for the spinning disc. Thus a substantial number of precision moving parts are required. Such units are therefore relatively expensive to construct and to maintain.
A less complicated cup bead or line former is disclosed in U.S. Pat. No. 4,247,277 which issued Jan. 27, 1981 to Marion. This patent describes an apparatus for forming a fill line or groove in paper cups or containers by axially compressing an annulus of a resilient material thereby causing a controlled deformation of the material outwardly about its periphery. The outward deformation occurs internally of a cup pot or die which includes an internal fill line or groove defining cavity into which a portion of the sidewall of a paper cup or container confined within the die is forced by the compressed annulus to form the fill line or groove. While this apparatus is less complicated than the spinning forming discs previously used for the same purpose, it is still a complicated apparatus which requires moving parts that tend to wear, require maintenance and replacement.
Forming techniques are also known in the pipe finishing arts. Exemplary of pipe finishing apparatus are taught in U.S. Pat. No. 3,570,065 which issued on Mar. 16, 1971 to Guerrero; U.S. Pat. No. 3,923,952 which issued Dec. 2, 1975 to LaBranche et al.; and, U.S. Pat. No. 3,823,216 which issued Jul. 9, 1974 to Petzetakis. Each of those patents teach an apparatus for shaping a normally rigid plastic pipe which includes an expandable elastomeric forming member. Each of the apparatus also includes a leading portion having an outer diameter corresponding to the internal diameter of the undeformed pipe and a trailing portion which expands the pipe to form a belied coupling.
All of the known apparatus in the prior art include moving parts for forming a fill line in a paper cup or a bell in a pipe coupling.
Accordingly, it is a primary object of the present invention to provide a simplified apparatus for forming a fill line in a paper container such as a paper cup.
It is a further object of the invention to provide an apparatus for forming a fill line in a paper container such as a paper cup which is inexpensive to manufacture and requires substantially no maintenance.